Avectra, vendor of one of the major association management systems, has launched a public wiki to support their products.
This is the first public wiki to support an association-dedicated product that I am aware of. I think there is a good chance this will build critical mass with their customers. Association staff are going to have high incentive to contribute since this is such a major part of their management systems yet there are few to no resources, such as commercially published books, on the subject.
It might work better if the user groups dedicated to the AMS vendors launched their own wikis, maintaining some independence.